From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77A98C433E0 for ; Mon, 3 Aug 2020 12:59:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F63B20678 for ; Mon, 3 Aug 2020 12:59:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726929AbgHCM7U (ORCPT ); Mon, 3 Aug 2020 08:59:20 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2557 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726478AbgHCM7T (ORCPT ); Mon, 3 Aug 2020 08:59:19 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id A8DF816A36FAD6C13464; Mon, 3 Aug 2020 13:59:18 +0100 (IST) Received: from [127.0.0.1] (10.210.168.55) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Mon, 3 Aug 2020 13:59:17 +0100 Subject: Re: [PATCH 4.14 01/51] scsi: libsas: direct call probe and destruct To: Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" CC: "stable@vger.kernel.org" , yanaijie , Johannes Thumshirn , Ewan Milne , Christoph Hellwig , Tomas Henzl , Dan Williams , Hannes Reinecke , "Martin K. Petersen" , Sasha Levin References: <20200803121849.488233135@linuxfoundation.org> <20200803121849.564535738@linuxfoundation.org> From: John Garry Message-ID: <8743227b-adb3-ed1f-3559-e562555ac045@huawei.com> Date: Mon, 3 Aug 2020 13:57:14 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20200803121849.564535738@linuxfoundation.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.210.168.55] X-ClientProxiedBy: lhreml726-chm.china.huawei.com (10.201.108.77) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/08/2020 13:19, Greg Kroah-Hartman wrote: > From: Jason Yan > > [ Upstream commit 0558f33c06bb910e2879e355192227a8e8f0219d ] > Hi Greg, This patch was one of a series from Jason to fix this WARN issue, below: https://lore.kernel.org/linux-scsi/8f6e3763-2b04-23e8-f1ec-8ed3c58f55d3@huawei.com/ I'm doubtful that it should be taken in isolation. Maybe 1 or 2 other patches are required. The WARN was really annoying, so we could spend a bit of time to test a backport of what is strictly required. Let us know. Thanks, John > In commit 87c8331fcf72 ("[SCSI] libsas: prevent domain rediscovery > competing with ata error handling") introduced disco mutex to prevent > rediscovery competing with ata error handling and put the whole > revalidation in the mutex. But the rphy add/remove needs to wait for the > error handling which also grabs the disco mutex. This may leads to dead > lock.So the probe and destruct event were introduce to do the rphy > add/remove asynchronously and out of the lock. > > The asynchronously processed workers makes the whole discovery process > not atomic, the other events may interrupt the process. For example, > if a loss of signal event inserted before the probe event, the > sas_deform_port() is called and the port will be deleted. > > And sas_port_delete() may run before the destruct event, but the > port-x:x is the top parent of end device or expander. This leads to > a kernel WARNING such as: > > [ 82.042979] sysfs group 'power' not found for kobject 'phy-1:0:22' > [ 82.042983] ------------[ cut here ]------------ > [ 82.042986] WARNING: CPU: 54 PID: 1714 at fs/sysfs/group.c:237 > sysfs_remove_group+0x94/0xa0 > [ 82.043059] Call trace: > [ 82.043082] [] sysfs_remove_group+0x94/0xa0 > [ 82.043085] [] dpm_sysfs_remove+0x60/0x70 > [ 82.043086] [] device_del+0x138/0x308 > [ 82.043089] [] sas_phy_delete+0x38/0x60 > [ 82.043091] [] do_sas_phy_delete+0x6c/0x80 > [ 82.043093] [] device_for_each_child+0x58/0xa0 > [ 82.043095] [] sas_remove_children+0x40/0x50 > [ 82.043100] [] sas_destruct_devices+0x64/0xa0 > [ 82.043102] [] process_one_work+0x1fc/0x4b0 > [ 82.043104] [] worker_thread+0x50/0x490 > [ 82.043105] [] kthread+0xfc/0x128 > [ 82.043107] [] ret_from_fork+0x10/0x50 > > Make probe and destruct a direct call in the disco and revalidate function, > but put them outside the lock. The whole discovery or revalidate won't > be interrupted by other events. And the DISCE_PROBE and DISCE_DESTRUCT > event are deleted as a result of the direct call. > > Introduce a new list to destruct the sas_port and put the port delete after > the destruct. This makes sure the right order of destroying the sysfs > kobject and fix the warning above. > > In sas_ex_revalidate_domain() have a loop to find all broadcasted > device, and sometimes we have a chance to find the same expander twice. > Because the sas_port will be deleted at the end of the whole revalidate > process, sas_port with the same name cannot be added before this. > Otherwise the sysfs will complain of creating duplicate filename. Since > the LLDD will send broadcast for every device change, we can only > process one expander's revalidation. > > [mkp: kbuild test robot warning] > > Signed-off-by: Jason Yan > CC: John Garry > CC: Johannes Thumshirn > CC: Ewan Milne > CC: Christoph Hellwig > CC: Tomas Henzl > CC: Dan Williams > Reviewed-by: Hannes Reinecke > Signed-off-by: Martin K. Petersen > Signed-off-by: Sasha Levin > ---